The consistent temperature indicated by section 2 represents the flow of energy lost as the water freezes.
Section 2 indicates that energy is being utilized to bring all molecules to the melting point.
Section 4 indicates that the temperature is stable until all molecules reach the boiling point.
The increasing temperature in section 5 indicates that molecular motion is increasing.
Explanation:
The figure is missing: find it in attachment.
The graph represents the temperature of a block of ice as heat is continuously supplied to it.
At the beginning (section 1), the temperature increases: in this phase, the heat supplied to the ice is used to increase the kinetic energy of vibration of the molecules of ice.
When the ice reach point A (melting point), the ice starts to melt. In this phase (section 2), the temperature of the substance remains constant, because all the heat supplied is used to break the bonds between the molecules, converting the ice into liquid water.
At point B, the ice has completely melted, and therefore we now have liquid water.
In sector 3 (between B and C), the temperature of the water increases again as we supply more and more heat: this heat, in fact, is used to increase the kinetic energy of the molecules, which move faster and faster.
Then, the water reaches the boiling point (point C): after that, the water starts to boil, (sector 4) and the heat supplied is entirely used to remove the intermolecular forces between the molecules of water; as a result, the temperature remains constant during the process.
At poind D, the water has completely boiled, and converted into gas state (steam).
After that, the temperature of the steam starts to increase again (sector 5) as more and more heat is supplied, because it is used to increase the kinetic energy of the molecules.
Therefore, the correct statements are:
The consistent temperature indicated by section 2 represents the flow of energy lost as the water freezes.
Section 2 indicates that energy is being utilized to bring all molecules to the melting point.
Section 4 indicates that the temperature is stable until all molecules reach the boiling point.
The increasing temperature in section 5 indicates that molecular motion is increasing.
